DESCRIPTION: (Applicant's Description) MRI of the breast provides higher soft tissue contrast than conventional breast imaging (mammography). This provides the potential for improved lesion detection and characterization. Studies have already demonstrated the potential for breast MRI to distinguish benign from malignant breast lesions and to detect mammographically and clinically occult cancer. In response to RFA CA-96-012, a consortium of 14 clinical sites has been organized to perform a study on the performance characteristics of breast MRI in : detecting and diagnosing lesions in patients with suspicious mammographic or clinical findings and determining the extent of cancer within an affected breast. In addition to characterizing the performance of breast MRI as described above, factors affecting the performance such as prior knowledge of historical and mammographic features will also be evaluated. In particular, the relative importance of high resolution and dynamic imaging will be assessed. In addition, this consortium will conduct a pilot study to investigate the feasibility of screening patients that carry a breast cancer susceptibility gene with MRI. The 14 clinical sites provide experts in breast imaging, clinical MRI and MR physics to serve on the Executive and Quality Assurance committees. In addition to the clinical sites, the consortium contains mammography, and pathology Quality Assurance facilities to support this trial. The consortium has formed strategic partnerships with industry in order to acquire technical expertise in the MRI equipment used in this study and to acquire the contrast agents to be used in the study. The expertise represented in the consortium and its industry partners makes it uniquely qualified to carry out this research program.